Have a few legendary musicians providing entertainment. Sure they're damned, but at the moment they look sleek and well taken care of.
If you really want the players to consider taking the bargain, then let them negotiate an escape clause. E.g. if they win, then they can reclaim their souls by doing Dispater a favor sometime in a fixed term... or the contract is void if Dispater fails to fulfil a future service (which the party might think they can trick him out of doing).
Legendary musicians could be very good, especially ones who died or vanished tragically young and are considered lost. My elven noble is a bard, so it would resonate with her if there were elves there, I think. As for the contract addendum or condition, that could be devilish fun, negotiating clauses. We'll see how negotiatory my players feel.
This is a brilliant idea. If it were me, I'd include lots of persons from their past attending or possibly serving: people they've killed, family members, vanquished villains, etc.
I do have a PC who was banished to the Abyss, I may have him put in an appearance in the entourage of a prominent devil who rescued him from the demons. Or maybe he rescued the devil and got taken in as a reward. Either way, he'll be a fun NPC to present.
I can't think of any suitable villains to really bring into play.
Dispater is godlike in terms of personal power in Dis, and if he's throwing the PCs a banquet, ask yourself what he intends to get from it that he couldn't get simply be killing them and taking their souls by brute imposition of his will? Perhaps he could do just that, and perhaps he could imply that as well. But you know, that wouldn't be polite and proper for an entity of his stature and sublime grace. The other Lords of the 9 might be so crass, but he's better than that, wouldn't you agree?
The banquet should be all about showing off Dispater's power and a monument to what sort of being he is. Given that the PCs are mortal, he'll probably dispense with overt bloodshed and stereotypical hellish scenery, because that would be cliche. He'll want to keep the PCs unbalanced a touch, just to make them entirely uncertain how to react to him and thus allow him the opportunity to ensure that they react to him rather than him to them. He's a devil and so it's all about control, and the entire event should be used to show just how much in control he is of events, even if it's not real in any particular event, even if it's based on lies, even if the chains are imagined rather than physical.
This is exactly what I hoped to get out of this thread, thanks Shemeska!
Dispater's motivations are simple (and informed by the adventure itself, actually); he wants Tiamat not to escape Avernus, and to continue to be a nuisance to Zariel, the ruler of the first level of hell. Therefore he has agreed to commit a legion of devils to the conflict. Any of his devils slain will merely reappear in the nine hells. And, I suspect, he enjoys the thought that no mortal can deny that he
saved them. That they owe a great deal of praise to Dispater for their victory.
I have a few ideas for how Dispater could show his control. I plan to have him (or his Viceroy, if he's absent) to command a pit fiend to battle the PCs to the death. A cruel fate for the devil, and a display for his guests of the prowess of these mortals (who will dance for him, slaying a pit fiend who has displeased him). It will also let me throw in some combat without doing some hackneyed ambush in the middle of the dinner.
In addition, I plan for Dispater (or his Viceroy) to offer the PCs some liquor distilled from souls.
"That's an aged Cain Devonbrook of Cormyr, blond and bearded with a light hint of valor and strong undercurrents of justice. Notice how the devotion breaks on the tongue, giving the sweet taste of despair at the end?" Purely a display of opulence and wealth, and a step towards corrupting any mortal who dines with him.
Note that Dispater is very Paranoid and never leaves his Tower...
Sir, this information is
invaluable. Thank you for such wonderful, detailed information, both on Dispater and his court, and on the city itself. I had only read the snippets from the 5th Edition DMG, which is more of an overview than a detailed character study. Where is this information from? I may have to look this book up, particularly if I plan to bring in Mephistopholes (which would, admittedly, be tremendous fun).
I'm on the fence now about whether I want Dispater to show his face or not. If he does, however, it will likely be in close company and not at the party at large. Playing up the hatred of the Viceroy by the guests could provide a nice undercurrent of intrigue to the party.
I expect it would be endless.
...
- The banquet is served by male and female beings of perfect form and beauty, nearly nude, hinting, teasing, and remaining tantilizingly out of reach.
...
- Dinner conversation is an unending stream of self-indulgent one-upsmanship.
Perception of time is definitely something I want to play with. It feels fitting that time would be altered in this place, that a banquet would stretch on for what feels like days, while mere hours have played out. And snide one-upsmanship and self-indulgent discussion would certainly be fun to play. Especially directed at the PCs.
As for the help, they will certainly be slaves of peerless beauty, once again, to show off Dispater's opulence and wealth.